2006-12-19 19:38:12 · 13 answers · asked by srehvi 2 in Education & Reference ➔ Trivia
A round manhole cover cannot fall through its circular opening, whereas a square manhole cover may fall in if it were inserted diagonally in the aperture (A Reuleaux triangle or other curve of constant width would also serve this purpose, but round covers are much easier to manufacture.)
Round tubes are the strongest and most material-efficient shape against the compression of the earth around them, and so it is natural that the cover of a round tube assume a circular shape.
Cylindrical holes are easier to dig.
The bearing surfaces of manhole frames and covers are machined to assure flatness and prevent them from becoming dislodged by traffic.
Round castings are much easier to machine using horizontal boring mills.
Circular covers do not need to be rotated to align them when covering a circular manhole.
Human beings have a roughly circular cross-section.
A round manhole cover can be more easily moved by being rolled.
If a automobile rolls over a dislodged manhole of another shape, the sharp corners could puncture the automobile's tire, whereas a circle doesn't have corners.
2006-12-19 19:40:19 · answer #1 · answered by Anonymous · 6⤊ 1⤋
The shape is important since all manholes must have covers. The circle is the only shape that prevents the manhole covers from falling in if they are moved. Every other shape (square, triangle, octagon, etc) can be tilted and fall into the manhole. For safety, then, manholes have to be circular.
2006-12-19 19:42:02 · answer #2 · answered by cedrdar 1 · 2⤊ 0⤋
So that you can't drop the cover down the manhole, which is smaht cuz those things is HEAVY! Most cisterns (the shaft accessed by the manhole) are actually square.
2006-12-20 04:51:11 · answer #3 · answered by Timothy S 3 · 0⤊ 0⤋
Heavy, round manhole covers are easier for one person to move by standing it on end and rolling. Also, you don't have to "align" a manhole cover to it's hole ... any orientation will do.
2006-12-19 19:47:49 · answer #4 · answered by Twisted Maggie 6 · 1⤊ 0⤋
A manhole is round because turds are cylindrical in shape making them easier to slide out.
Remember any hole is a goal, but not a manhole!
2006-12-19 19:46:46 · answer #5 · answered by Darren R 1 · 0⤊ 3⤋
The lids cant fall through a round hole .
2006-12-19 19:41:14 · answer #6 · answered by Mad Dog Johnson 4 · 3⤊ 0⤋
So a person can fit in it. Plus, Cylinders are easier to make than square holes.
2006-12-19 19:40:04 · answer #7 · answered by Redeemer 5 · 0⤊ 0⤋
We are supposed to call them 'Personnel Access Chambers' now. PC gone mad
Why is an egg egg shaped?
2006-12-19 21:35:19 · answer #8 · answered by Basement Bob 6 · 1⤊ 0⤋
Through much trial and era it was found that a circle will not fall through its opening.
2006-12-21 06:37:17 · answer #9 · answered by Anonymous · 0⤊ 0⤋
so the lid cant possible fall down inside of it
2006-12-22 21:23:47 · answer #10 · answered by william_callen 2 · 0⤊ 0⤋